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Zlatko Čalušić c70bc7ed0b Document REST backend

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2016-12-31 13:14:44 +01:00

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Thanks for using restic. This document will give you an overview of the basic functionality provided by restic.

Building/installing restic

If you are using Mac OS X, you can install restic using the homebrew packet manager:

$ brew tap restic/restic
$ brew install restic

On archlinux, there is a package called restic-git which can be installed from AUR, e.g. with pacaur:

$ pacaur -S restic-git

At debian stable you can install 'go' directly from the repositories (as root):

$ apt-get install golang-go

after installation of 'go' go straight forward to 'git clone [...]'

If you are using Linux, BSD or Windows, the only way to install restic on your system right now is to compile it from source. restic is written in the Go programming language and you need at least Go version 1.6. Building restic may also work with older versions of Go, but that's not supported. See the Getting started guide of the Go project for instructions how to install Go.

In order to build restic from source, execute the following steps:

$ git clone https://github.com/restic/restic
[...]

$ cd restic

$ go run build.go

At the moment, the only tested compiler for restic is the official Go compiler. Building restic with gccgo may work, but is not supported.

Usage help is available:

$ ./restic --help
restic is a backup program which allows saving multiple revisions of files and
directories in an encrypted repository stored on different backends.

Usage:
  restic [command]

Available Commands:
  backup        create a new backup of files and/or directories
  cat           print internal objects to stdout
  check         check the repository for errors
  find          find a file or directory
  forget        forget removes snapshots from the repository
  init          initialize a new repository
  key           manage keys (passwords)
  list          list items in the repository
  ls            list files in a snapshot
  mount         mount the repository
  prune         remove unneeded data from the repository
  rebuild-index build a new index file
  restore       extract the data from a snapshot
  snapshots     list all snapshots
  unlock        remove locks other processes created
  version       Print version information

Flags:
      --no-lock                do not lock the repo, this allows some operations on read-only repos
  -p, --password-file string   read the repository password from a file
  -q, --quiet                  do not outputcomprehensive progress report
  -r, --repo string            repository to backup to or restore from (default: $RESTIC_REPOSITORY)

Use "restic [command] --help" for more information about a command.

Similar to programs such as git, restic has a number of sub-commands. You can see these commands in the listing above. Each sub-command may have own command-line options, and there is a help option for each command which lists them, e.g. for the backup command:

$ ./restic backup --help
The "backup" command creates a new snapshot and saves the files and directories
given as the arguments.

Usage:
  restic backup [flags] FILE/DIR [FILE/DIR] ...

Flags:
  -e, --exclude pattern         exclude a pattern (can be specified multiple times)
      --exclude-file string     read exclude patterns from a file
      --files-from string       read the files to backup from file (can be combined with file args)
  -f, --force                   force re-reading the target files/directories. Overrides the "parent" flag
  -x, --one-file-system         Exclude other file systems
      --parent string           use this parent snapshot (default: last snapshot in the repo that has the same target files/directories)
      --stdin                   read backup from stdin
      --stdin-filename string   file name to use when reading from stdin
      --tag tag                 add a tag for the new snapshot (can be specified multiple times)

Global Flags:
      --no-lock                do not lock the repo, this allows some operations on read-only repos
  -p, --password-file string   read the repository password from a file
  -q, --quiet                  do not outputcomprehensive progress report
  -r, --repo string            repository to backup to or restore from (default: $RESTIC_REPOSITORY)

Subcommand that support showing progress information such as backup, check and prune will do so unless the quiet flag -q or --quiet is set. When running from a non-interactive console progress reporting will be limited to once every 10 seconds to not fill your logs.

Additionally on Unix systems if restic receives a SIGUSR signal the current progress will written to the standard output so you can check up on the status at will.

Initialize a repository

First, we need to create a "repository". This is the place where your backups will be saved at.

In order to create a repository at /tmp/backup, run the following command and enter the same password twice:

$ restic init --repo /tmp/backup
enter password for new backend:
enter password again:
created restic backend 085b3c76b9 at /tmp/backup
Please note that knowledge of your password is required to access the repository.
Losing your password means that your data is irrecoverably lost.

Remembering your password is important! If you lose it, you won't be able to access data stored in the repository.

For automated backups, restic accepts the repository location in the environment variable RESTIC_REPOSITORY. The password can be read from a file (via the option --password-file) or the environment variable RESTIC_PASSWORD.

Password prompt on Windows

At the moment, restic only supports the default Windows console interaction. If you use emulation environments like MSYS2 or Cygwin, which use terminals like Mintty or rxvt, you may get a password error:

You can workaround this by using a special tool called winpty (look here and here for detail information). On MSYS2, you can install winpty as follows:

$ pacman -S winpty
$ winpty restic -r /tmp/backup init

Create a snapshot

Now we're ready to backup some data. The contents of a directory at a specific point in time is called a "snapshot" in restic. Run the following command and enter the repository password you chose above again:

$ restic -r /tmp/backup backup ~/work
enter password for repository:
scan [/home/user/work]
scanned 764 directories, 1816 files in 0:00
[0:29] 100.00%  54.732 MiB/s  1.582 GiB / 1.582 GiB  2580 / 2580 items  0 errors  ETA 0:00
duration: 0:29, 54.47MiB/s
snapshot 40dc1520 saved

As you can see, restic created a backup of the directory and was pretty fast! The specific snapshot just created is identified by a sequence of hexadecimal characters, 40dc1520 in this case.

If you run the command again, restic will create another snapshot of your data, but this time it's even faster. This is de-duplication at work!

$ restic -r /tmp/backup backup ~/shared/work/web
enter password for repository:
using parent snapshot 40dc1520aa6a07b7b3ae561786770a01951245d2367241e71e9485f18ae8228c
scan [/home/user/work]
scanned 764 directories, 1816 files in 0:00
[0:00] 100.00%  0B/s  1.582 GiB / 1.582 GiB  2580 / 2580 items  0 errors  ETA 0:00
duration: 0:00, 6572.38MiB/s
snapshot 79766175 saved

You can even backup individual files in the same repository.

$ restic -r /tmp/backup backup ~/work.txt
scan [~/work.txt]
scanned 0 directories, 1 files in 0:00
[0:00] 100.00%  0B/s  220B / 220B  1 / 1 items  0 errors  ETA 0:00
duration: 0:00, 0.03MiB/s
snapshot 31f7bd63 saved

In fact several hosts may use the same repository to backup directories and files leading to a greater de-duplication.

You can exclude folders and files by specifying exclude-patterns. Either specify them with multiple --exclude's or one --exclude-file

$ cat exclude
# exclude go-files
*.go
# exclude foo/x/y/z/bar foo/x/bar foo/bar
foo/**/bar
$ restic -r /tmp/backup backup ~/work --exclude=*.c --exclude-file=exclude

Patterns use filepath.Glob internally, see filepath.Match for syntax. Additionally ** exludes arbitrary subdirectories. Environment-variables in exclude-files are expanded with os.ExpandEnv.

By specifying the option --one-file-system you can instruct restic to only backup files from the file systems the initially specified files or directories reside on. For example, calling restic like this won't backup /sys or /dev on a Linux system:

$ restic -r /tmp/backup backup --one-file-system /

By using the --files-from option you can read the files you want to backup from a file. This is especially useful if a lot of files have to be backed up that are not in the same folder or are maybe pre-filtered by other software.

For example maybe you want to backup files that have a certain filename in them:

$ find /tmp/somefiles | grep 'PATTERN' > /tmp/files_to_backup

You can then use restic to backup the filtered files:

$ restic -r /tmp/backup backup --files-from /tmp/files_to_backup

Incidentally you can also combine --files-from with the normal files args:

$ restic -r /tmp/backup backup --files-from /tmp/files_to_backup /tmp/some_additional_file

Reading data from stdin

Sometimes it can be nice to directly save the output of a program, e.g. mysqldump so that the SQL can later be restored. Restic supports this mode of operation, just supply the option --stdin to the backup command like this:

$ mysqldump [...] | restic -r /tmp/backup backup --stdin

This creates a new snapshot of the output of mysqldump. You can then use e.g. the fuse mounting option (see below) to mount the repository and read the file.

By default, the file name stdin is used, a different name can be specified with --stdin-filename, e.g. like this:

$ mysqldump [...] | restic -r /tmp/backup backup --stdin --stdin-filename production.sql

List all snapshots

Now, you can list all the snapshots stored in the repository:

$ restic -r /tmp/backup snapshots
enter password for repository:
ID        Date                 Host    Tags   Directory
----------------------------------------------------------------------
40dc1520  2015-05-08 21:38:30  kasimir        /home/user/work
79766175  2015-05-08 21:40:19  kasimir        /home/user/work
bdbd3439  2015-05-08 21:45:17  luigi          /home/art
590c8fc8  2015-05-08 21:47:38  kazik          /srv
9f0bc19e  2015-05-08 21:46:11  luigi          /srv

You can filter the listing by directory path:

$ restic -r /tmp/backup snapshots --path="/srv"
enter password for repository:
ID        Date                 Host    Tags   Directory
----------------------------------------------------------------------
590c8fc8  2015-05-08 21:47:38  kazik          /srv
9f0bc19e  2015-05-08 21:46:11  luigi          /srv

Or filter by host:

$ restic -r /tmp/backup snapshots --host luigi
enter password for repository:
ID        Date                 Host    Tags   Directory
----------------------------------------------------------------------
bdbd3439  2015-05-08 21:45:17  luigi          /home/art
9f0bc19e  2015-05-08 21:46:11  luigi          /srv

Combining filters is also possible.

Restore a snapshot

Restoring a snapshot is as easy as it sounds, just use the following command to restore the contents of the latest snapshot to /tmp/restore-work:

$ restic -r /tmp/backup restore 79766175 --target ~/tmp/restore-work
enter password for repository:
restoring <Snapshot of [/home/user/work] at 2015-05-08 21:40:19.884408621 +0200 CEST> to /tmp/restore-work

Use the word latest to restore the last backup. You can also combine latest with the --host and --path filters to choose the last backup for a specific host, path or both.

$ restic -r /tmp/backup restore latest --target ~/tmp/restore-work --path "/home/art" --host luigi
enter password for repository:
restoring <Snapshot of [/home/art] at 2015-05-08 21:45:17.884408621 +0200 CEST> to /tmp/restore-work

Manage repository keys

The key command allows you to set multiple access keys or passwords per repository. In fact, you can use the list, add, remove and passwd sub-commands to manage these keys very precisely:

$ restic -r /tmp/backup key list
enter password for repository:
 ID          User        Host        Created
----------------------------------------------------------------------
*eb78040b    username    kasimir   2015-08-12 13:29:57

$ restic -r /tmp/backup key add
enter password for repository:
enter password for new key:
enter password again:
saved new key as <Key of username@kasimir, created on 2015-08-12 13:35:05.316831933 +0200 CEST>

$ restic -r backup key list
enter password for repository:
 ID          User        Host        Created
----------------------------------------------------------------------
 5c657874    username    kasimir   2015-08-12 13:35:05
*eb78040b    username    kasimir   2015-08-12 13:29:57

Check integrity and consistency

Imagine your repository is saved on a server that has a faulty hard drive, or even worse, attackers get privileged access and modify your backup with the intention to make you restore malicious data:

$ sudo echo "boom" >> backup/index/d795ffa99a8ab8f8e42cec1f814df4e48b8f49129360fb57613df93739faee97

In order to detect these things, it is a good idea to regularly use the check command to test whether everything is alright, your precious backup data is consistent and the integrity is unharmed:

$ restic -r /tmp/backup check
Load indexes
ciphertext verification failed

Trying to restore a snapshot which has been modified as shown above will yield the same error:

$ restic -r /tmp/backup restore 79766175 --target ~/tmp/restore-work
Load indexes
ciphertext verification failed

Mount a repository

Browsing your backup as a regular file system is also very easy. First, create a mount point such as /mnt/restic and then use the following command to serve the repository with FUSE:

$ mkdir /mnt/restic
$ restic -r /tmp/backup mount /mnt/restic
enter password for repository:
Now serving /tmp/backup at /tmp/restic
Don't forget to umount after quitting!

Mounting repositories via FUSE is not possible on Windows and OpenBSD.

Create an SFTP repository

In order to backup data via SFTP, you must first set up a server with SSH and let it know your public key. Passwordless login is really important since restic fails to connect to the repository if the server prompts for credentials.

Once the server is configured, the setup of the SFTP repository can simply be achieved by changing the URL scheme in the init command:

$ restic -r sftp:user@host:/tmp/backup init
enter password for new backend:
enter password again:
created restic backend f1c6108821 at sftp:user@host:/tmp/backup
Please note that knowledge of your password is required to access the repository.
Losing your password means that your data is irrecoverably lost.

You can also specify a relative (read: no slash (/) character at the beginning) directory, in this case the dir is relative to the remote user's home directory.

Create a REST server repository

In order to backup data to the remote server via HTTP or HTTPS protocol, you must first set up a remote REST server instance. Once the server is configured, accessing it is achieved by changing the URL scheme like this:

$ restic -r rest:http://host:8000/

Depending on your REST server setup, you can use HTTPS protocol, password protection, or multiple repositories. Or any combination of those features, as you see fit. TCP/IP port is also configurable. Here are some more examples:

$ restic -r rest:https://host:8000/
$ restic -r rest:https://user:pass@host:8000/
$ restic -r rest:https://user:pass@host:8000/my_backup_repo/

If you use TLS, make sure your certificates are signed, 'cause restic client will refuse to communicate otherwise. It's easy to obtain such certificates today, thanks to free certificate authorities like Let’s Encrypt.

REST server uses exactly the same directory structure as local backend, so you should be able to access it both locally and via HTTP, even simultaneously.

Create an Amazon S3 repository

Restic can backup data to any Amazon S3 bucket. However, in this case, changing the URL scheme is not enough since Amazon uses special security credentials to sign HTTP requests. By consequence, you must first setup the following environment variables with the credentials you obtained while creating the bucket.

$ export AWS_ACCESS_KEY_ID=<MY_ACCESS_KEY>
$ export AWS_SECRET_ACCESS_KEY=<MY_SECRET_ACCESS_KEY>

You can then easily initialize a repository that uses your Amazon S3 as a backend, if the bucket does not exist yet it will be created in the default location:

$ restic -r s3:s3.amazonaws.com/bucket_name init
enter password for new backend:
enter password again:
created restic backend eefee03bbd at s3:s3.amazonaws.com/bucket_name
Please note that knowledge of your password is required to access the repository.
Losing your password means that your data is irrecoverably lost.

It is not possible at the moment to have restic create a new bucket in a different location, so you need to create it using a different program. Afterwards, the S3 server (s3.amazonaws.com) will redirect restic to the correct endpoint.

For an S3-compatible server that is not Amazon (like Minio, see below), or is only available via HTTP, you can specify the URL to the server like this: s3:http://server:port/bucket_name.

Create a Minio Server repository

Minio is an Open Source Object Storage, written in Go and compatible with AWS S3 API.

Pre-Requisites

Download and Install Minio Server.
You can also refer to https://docs.minio.io for step by step guidance on installation and getting started on Minio CLient and Minio Server.

You must first setup the following environment variables with the credentials of your running Minio Server.

$ export AWS_ACCESS_KEY_ID=<YOUR-MINIO-ACCESS-KEY-ID>
$ export AWS_SECRET_ACCESS_KEY= <YOUR-MINIO-SECRET-ACCESS-KEY>

Now you can easily initialize restic to use Minio server as backend with this command.

$ ./restic -r s3:http://localhost:9000/restic init
enter password for new backend:
enter password again:
created restic backend 6ad29560f5 at s3:http://localhost:9000/restic1
Please note that knowledge of your password is required to access
the repository. Losing your password means that your data is irrecoverably lost.

Removing old snapshots

All backup space is finite, so restic allows removing old snapshots. This can be done either manually (by specifying a snapshot ID to remove) or by using a policy that describes which snapshots to forget. For all remove operations, two commands need to be called in sequence: forget to remove a snapshot and prune to actually remove the data that was referenced by the snapshot from the repository.

Remove a single snapshot

The command snapshots can be used to list all snapshots in a repository like this:

$ restic -r /tmp/backup snapshots
enter password for repository:
ID        Date                 Host      Tags  Directory
----------------------------------------------------------------------
40dc1520  2015-05-08 21:38:30  kasimir         /home/user/work
79766175  2015-05-08 21:40:19  kasimir         /home/user/work
bdbd3439  2015-05-08 21:45:17  luigi           /home/art
590c8fc8  2015-05-08 21:47:38  kazik           /srv
9f0bc19e  2015-05-08 21:46:11  luigi           /srv

In order to remove the snapshot of /home/art, use the forget command and specify the snapshot ID on the command line:

$ restic -r /tmp/backup forget bdbd3439
enter password for repository:
removed snapshot d3f01f63

Afterwards this snapshot is removed:

$ restic -r /tmp/backup snapshots
enter password for repository:
ID        Date                 Host     Tags  Directory
----------------------------------------------------------------------
40dc1520  2015-05-08 21:38:30  kasimir        /home/user/work
79766175  2015-05-08 21:40:19  kasimir        /home/user/work
590c8fc8  2015-05-08 21:47:38  kazik          /srv
9f0bc19e  2015-05-08 21:46:11  luigi          /srv

But the data that was referenced by files in this snapshot is still stored in the repository. To cleanup unreferenced data, the prune command must be run:

$ restic -r /tmp/backup prune
enter password for repository:

counting files in repo
building new index for repo
[0:00] 100.00%  22 / 22 files
repository contains 22 packs (8512 blobs) with 100.092 MiB bytes
processed 8512 blobs: 0 duplicate blobs, 0B duplicate
load all snapshots
find data that is still in use for 1 snapshots
[0:00] 100.00%  1 / 1 snapshots
found 8433 of 8512 data blobs still in use
will rewrite 3 packs
creating new index
[0:00] 86.36%  19 / 22 files
saved new index as 544a5084
done

Afterwards the repository is smaller.

Removing snapshots according to a policy

Removing snapshots manually is tedious and error-prone, therefore restic allows specifying which snapshots should be removed automatically according to a policy. You can specify how many hourly, daily, weekly, monthly and yearly snapshots to keep, any other snapshots are removed. The most important command-line parameter here is --dry-run which instructs restic to not remove anything but print which snapshots would be removed.

When forget is run with a policy, restic loads the list of all snapshots, then groups these by host name and list of directories. The policy is then applied to each group of snapshots separately. This is a safety feature.

The forget command accepts the following parameters:

--keep-last n never delete the n last (most recent) snapshots
--keep-hourly n for the last n hours in which a snapshot was made, keep only the last snapshot for each hour.
--keep-daily n for the last n days which have one or more snapshots, only keep the last one for that day.
--keep-weekly n for the last n weeks which have one or more snapshots, only keep the last one for that week.
--keep-monthly n for the last n months which have one or more snapshots, only keep the last one for that month.
--keep-yearly n for the last n years which have one or more snapshots, only keep the last one for that year.
--keep-tag keep all snapshots which have all tags specified by this option (can be specified multiple times).

Additionally, you can restrict removing snapshots to those which have a particular hostname with the --hostname parameter, or tags with the --tag option. When multiple tags are specified, only the snapshots which have all the tags are considered.

All the --keep-* options above only count hours/days/weeks/months/years which have a snapshot, so those without a snapshot are ignored.

Let's explain this with an example: Suppose you have only made a backup on each Sunday for 12 weeks. Then forget --keep-daily 4 will keep the last four snapshots for the last four Sundays, but remove the rest. Only counting the days which have a backup and ignore the ones without is a safety feature: it prevents restic from removing many snapshots when no new ones are created. If it was implemented otherwise, running forget --keep-daily 4 on a Friday would remove all snapshots!

Debugging restic

The program can be built with debug support like this:

$ go run build.go -tags debug

Afterwards, extensive debug messages are written to the file in environment variable DEBUG_LOG, e.g.:

$ DEBUG_LOG=/tmp/restic-debug.log restic backup ~/work

If you suspect that there is a bug, you can have a look at the debug log. Please be aware that the debug log might contain sensitive information such as file and directory names.

The debug log will always contain all log messages restic generates. You can also instruct restic to print some or all debug messages to stderr. These can also be limited to e.g. a list of source files or a list of patterns for function names. The patterns are globbing patterns (see the documentation for path.Glob), multiple patterns are separated by commas. Patterns are case sensitive.

Printing all log messages to the console can be achieved by setting the file filter to *:

$ DEBUG_FILES=* restic check

If you want restic to just print all debug log messages from the files main.go and lock.go, set the environment variable DEBUG_FILES like this:

$ DEBUG_FILES=main.go,lock.go restic check

The following command line instructs restic to only print debug statements originating in functions that match the pattern *unlock* (case sensitive):

$ DEBUG_FUNCS=*unlock* restic check

Under the hood: Browse repository objects

Internally, a repository stores data of several different types described in the design documentation. You can list objects such as blobs, packs, index, snapshots, keys or locks with the following command:

$ restic -r /tmp/backup list snapshots
d369ccc7d126594950bf74f0a348d5d98d9e99f3215082eb69bf02dc9b3e464c

The find command searches for a given pattern in the repository.

$ restic -r backup find test.txt
debug log file restic.log
debug enabled
enter password for repository:
found 1 matching entries in snapshot 196bc5760c909a7681647949e80e5448e276521489558525680acf1bd428af36
  -rw-r--r--   501    20      5 2015-08-26 14:09:57 +0200 CEST path/to/test.txt

The cat command allows you to display the JSON representation of the objects or its raw content.

$ restic -r /tmp/backup cat snapshot d369ccc7d126594950bf74f0a348d5d98d9e99f3215082eb69bf02dc9b3e464c
enter password for repository:
{
  "time": "2015-08-12T12:52:44.091448856+02:00",
  "tree": "05cec17e8d3349f402576d02576a2971fc0d9f9776ce2f441c7010849c4ff5af",
  "paths": [
    "/home/user/work"
  ],
  "hostname": "kasimir",
  "username": "username",
  "uid": 501,
  "gid": 20
}

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